Health of­fi­cials aim­ing to pre­vent Zika’s spread

Dozens of cases found in state, but so far none trans­mit­ted by mos­qui­toes

Dozens of Mary­lan­ders have been found to carry the Zika virus, but none of those in­fec­tions have been trans­mit­ted by mos­qui­toes in the state, ac­cord­ing to health of­fi­cials.

Those of­fi­cials would not say this week whether or not any South­ern Mary­land res­i­dents are among those re­ported to be in­fected, cit­ing pa­tient pri­vacy.

All 54 of the in­fec­tions re­ported as of Aug. 3 by the Mary­land Depart­ment of Health and Men­tal Hy­giene are as­so­ci­ated with travel to re­gions re­port­ing Zika out­breaks car­ried by mos­qui­toes, ac­cord­ing to the agency. That in­cludes most na­tions in Cen­tral and South Amer­ica and the Caribbean.

How­ever that range of mos­quito-borne in­fec­tions now in­cludes a neigh­bor­hood in Mi­ami, and the Cen­ters for Dis­ease Con­trol and Pre­ven­tion have is­sued a Zika-re­lated travel ad­vi­sory for that area, the first in the con­ti­nen­tal United States.

Mary­land’s Zika cases have been scat­tered all over the state, Dr. Howard Haft, deputy di­rec­tor of pub­lic health ser­vices for the state, said late Wed­nes­day af­ter­noon. He and oth­ers em­pha­sized that all the in­fec­tions found so far have been in peo­ple who trav­eled to ar­eas where there have been mos­quito-borne out­breaks, or who have had sex­ual re­la­tions with some­one who did.

Be­cause there are rela- tively few cases in Mary­land, it might be too easy to guess a per­son’s iden­tity based on travel his­tory, St. Mary’s County health of­fi­cials said, so in­for­ma­tion about where they were dis­cov­ered is not be­ing re­leased by the state in or­der to pro­tect con­fi­den­tial­ity.

How­ever, “that pol­icy would change,” Haft said, if mos­quito-borne cases sur­face in Mary­land, as they have in Mi­ami.

Head­ing off that pos­si­bil­ity is the cur­rent fo­cus of the state’s pub­lic health of­fi­cials, and of the Mary­land Depart­ment of Agri­cul­ture’s Mos­quito Con­trol Ad­min­is­tra­tion. “We’re work­ing hard to make sure that never hap­pens,” Brian Pren­der­gast, that agency’s pro­gram man­ager said this week.

But those ef­forts, which fo­cus on pre­vent­ing the spread of the species of the mos­qui­toes that can carry the virus, face chal­lenges.

Preg­nant women are at great­est risk from Zika, which has been linked to women giv­ing birth to ba­bies with a con­di­tion called mi­cro­cephaly, a birth de­fect where a baby’s head is smaller than ex­pected. St. Mary’s health of­fi­cials de­clined to say if any preg­nant women in Mary­land have been found to be in­fected with the virus, but are “strongly ad­vis­ing women who are preg­nant or women try­ing to be­come preg­nant not to travel to these ar­eas [where mos­quito-borne in­fec­tions have been found] or have un­pro­tected sex­ual in­ter­course with a per­son who has re­cently trav­eled to these ar­eas.”

Symp­toms of the virus can in­clude fever, joint pain, skin rash and con­junc­tivi­tis (red eyes), the St. Mary’s County Health Depart­ment said. The ill­ness is usu­ally mild with symp­toms last­ing from sev­eral days to a week.

How­ever those symp­toms only oc­cur in about 20 per­cent of peo­ple who have the virus. Since the other 80 per­cent of those in­fected with Zika show no symp­toms, there are al­most cer­tainly peo­ple in Mary­land car­ry­ing the virus who have not been di­ag­nosed.

Some­one who doesn’t know they have been in­fected could be bit­ten by a mos­quito, which could bite some­one a week later and trans­mit the virus to them, Haft ac­knowl­edged.

In the Zika cases that have been iden­ti­fied, he said, health of­fi­cials go door to door and tell any­one within a 150-yard ra­dius of that per­son’s home that they can, if they’d like, be tested for the virus. In those ar­eas they and mos­quito con­trol work­ers also help res­i­dents iden­tify places near their homes where the mos­qui­toes can breed.

There are be­tween 60 to 65 species of mos­qui­toes in Mary­land, Pren­der­gast said, but it’s the Asian tiger mos­quito that can trans­mit Zika from one per­son to an­other, and that species is “in­cred­i­bly com­mon” in Mary­land and lives in close as­so­ci­a­tion with peo­ple. It also bites peo­ple at times when other mos­qui­toes gen­er­ally don’t. “This is the most ag­gres­sive day­time mos­quito,” he said.

“These are not swamp mos­qui­toes; they are con­tainer mos­qui­toes,” Haft said.

That means they can lay eggs any­where there is as lit­tle as half an inch of stand­ing wa­ter — pud­dles, un­used toys, old tires, even bot­tle caps or in the folds of a dis­carded piece of plas­tic wrap.

These breed­ing habits make pre­ven­tion ef­forts dif­fi­cult, but it can also make them ef­fec­tive.

An Asian tiger mos­quito does not fly very far from where it is hatched, Pren­der­gast said, “so Mother Na­ture is do­ing us a fa­vor in that re­gard.” If peo­ple can be sure that there are none of these mos­qui­toes in their yard or the neigh­bor’s yard, the chance of be­com­ing in­fected with Zika is low, he said.

That’s why state health of­fi­cials zero in on the ar­eas near peo­ple who have been found to have the virus, and it’s why St. Mary’s health of­fi­cials and the lo­cal mos­quito con­trol of­fice is look­ing to stop Asian tiger mos­qui­toes from hatch­ing in other ar­eas as well.

So the St. Mary’s health depart­ment has been reach­ing out to neigh­bor­hood home­own­ers as­so­ci­a­tions to spread the word, she said. And about once a week, staffers from the health depart­ment, along with the Mary­land Depart­ment of Agri­cul­ture, have been go­ing door to door in a St. Mary’s neigh­bor­hood to pass out lit­era- ture, talk about pre­ven­tion of mos­quito breed­ing and even help res­i­dents check their prop­erty for stand­ing wa­ter. Once a week, empty, scrub, cover or throw out items that hold wa­ter, they ad­vise.

“We work with the health depart­ment to in­form peo­ple what to look for in their neigh­bor­hood,” Ralph Heard, who heads the mos­quito con­trol pro­gram in St. Mary’s and Charles coun­ties. Ev­ery year, his of­fice starts a lar­vi­cide pro­gram to kill newly hatched mos­qui­toes while they are still in the wa­ter.

“We have peo­ple got out and check ditches” and other stand­ing wa­ter, he said. That pro­gram be­gins in March. “We try to knock them down first that way.”

Trucks start spray­ing for mos­qui­toes the last week in June, he said. “We can’t get them all by lar­vi­cide.” Eight driv­ers hit 77 neigh­bor­hoods in St. Mary’s and 61 in Charles County at night once a week with an in­sec­ti­cide called per­manone. Neigh­bor­hood res­i­dents pay 100 per­cent of the cost of this spray­ing.

This year the threat of Zika has more peo­ple in­ter­ested in sign­ing up for the spray­ing pro­gram. About 30 or 40 neigh­bor­hoods have asked about it, ac­cord­ing to Greta Jones, who works in the mos­quito con­trol of­fice, but many of them say they can’t af­ford it. About 60 in­di­vid­u­als have checked about hav­ing their prop­erty sprayed, but that is even more ex­pen­sive. The cost was $800 for one home­owner who chose to have it done.

Spray­ing usu­ally runs un­til the end of Septem­ber, but Zika could ex­tend that longer. It takes a hard frost to kill mos­qui­toes, Heard said, and that some­times doesn’t come in South­ern Mary­land un­til Novem­ber.

Mean­while, health mos­quito con­trol of­fi­cials also em­pha­size to peo­ple how to pro­tect against mos­quito bites. That in­cludes us­ing screens on doors and win­dows and mak­ing sure any holes in those screens are re­paired. The health depart­ment also rec­om­mends us­ing an EPA-reg­is­tered in­sect re­pel­lent with DEET, pi­caridin, IR3535, or oil of lemon eu­ca­lyp­tus or para-men­thane-diol. For a list of EPA-reg­is­tered in­sect re­pel­lents, visit www. epa.gov. These re­pel­lents are ef­fec­tive and safe when used as di­rected, Prochnow said.

There is an on­go­ing dis­cus­sion in Mary­land about how to re­spond to the Zika virus, she said. “Strate­gies are al­ways chang­ing,” she said. “We are learn­ing so much more about this dis­ease.”